In the May 11 & 25 SN: High-tech cricket farming, AI learns from Minecraft, looking for lithium, a new hominid species is named, signs of life in dead pig brains, Cherokee cave texts decoded, water molecules on the moon and more.

WASHINGTON — Ancient people living in what’s now Mongolia drank milk from cows, yaks and sheep — even though, as adults, they couldn’t digest lactose. That finding comes from the humblest of sources: ancient dental plaque.

Modern Mongolians are big on dairy, milking seven different animal species, including cows, yaks and camels. But how far into the past that dairying tradition extends is difficult to glean from the usual archaeological evidence: Nomadic lifestyles mean no kitchen trash heaps preserving ancient pots with lingering traces of milk fats. So molecular anthropologist Christina Warinner and her colleagues turned to the skeletons found in 22 burial mounds belonging to the Deer Stone culture, a people who lived in Mongolia’s eastern steppes around about 1300 B.C.

The hardened dental plaque, or tartar, on the teeth of the skeletons contained traces of milk proteins, Warinner, of the Max Planck Institute for the Science of Human History in Jena, Germany, said February 16 at the annual meeting of the American Association for the Advancement of Science. Those proteins showed that the people drank milk from cows, yaks, goats and sheep, but not from camels or reindeer, which modern day Mongolians milk today.

Ancient Mongolians’ DNA also revealed that they weren’t able to digest lactose as adults. Instead, the Deer Stone people, like modern Mongolians, may have relied on bacteria within the gut, known as the gut microbiome, to break down the lactose, Warinner said.